code: def __init__(self):
      self.subtrees = []
      self.word = None
      self.label = ""
      self.parent = None
      self.span = (-1, -1)
      self.word_vector = None  # HOS, store dx1 RNN word vector
      self.prediction = None
  
imports: import logging
  import os
  import pickle
  from collections import Counter
  import numpy
  import torch
  from torch.utils import data
label_desc: Use image node_id 1 to create a new PTBTree object  with example: obj = PTBTree()